questions 7

Cardiomyopathies

Author:
Topic updated on 08/27/17 9:06am

Snapshot
  • A 17-year-old boy suddenly collapsed and died on the soccer field shortly after scoring the winning goal. He had no known past medical history. 
Introduction
  • Cardiomyopathies describes a group of intrinsic cardiac disorders that affects the myocardium
    • often results in symptoms secondary to heart failure
    • cardiomyopathies do not include alterations in the heart muscle that are secondary to hypertension, coronary artery disease, or valvular disorders
  • Three major categories include
    • Dilated cardiomyopathy
      • leads to impaired systolic contraction
    • Restrictive (infiltrative) cardiomyopathy
      • leads to impaired diastolic relaxation
    • Hypertrophic cardiomyopathy
      • leads to impaired diastolic relaxation
Dilated Cardiomyopathy (DCM)
  • Overview
    • Most common cardiomyopathy (~90% of cases)
      • leads to systolic dysfunction
      • due to ↓ contractility and resultant ↓ ejection fraction
  • Etiologies
    • idiopathic
    • genetic
      • mutations in proteins that affects the interaction between the cytoskeleton and sarcomere
      • dystrophin gene mutations
        • x-linked
    • toxins
      • alcohol abuse
        • via direct toxic damage to myocardium
        • associated thiamine deficiencyberiberi
      • doxorubicin toxicity
      • cobalt
    • infectious 
      • coxsackievirus
      • chagas' disease (in South America)
        • caused by protozoa Typanosoma cruzi
    • peripartum cardiomyopathy
  • Symptoms/Physical exam
    • ineffective contraction slowly progressive congestive heart failure
      • see Congestive Heart Failure
    • S3 heart sound & mitral regurgitation murmur
  • Evaluation
    • Echocardiography is definitive
      • shows dilated ventricles 
      • confirms decreased EF
    • CXR shows balloon-like heart
  • Treatment
    • ACEIs/ARBs
    • beta-blockers
    • spironolactone
    • digoxin for symptom improvement
      • does not improve mortality
Hypertrophic Cardiomyopathy (HCM)
  • Overview 
    • characterized by hypertrophy of the myocardium, a defect in diastolic filling, and ventricular outflow obstruction (in 1/3 of cases)
      • systolic function is usually preserved
      • high ejection fraction
    • cause of sudden death in young athletes 
      • thickened septal wall too close to the anterior leaflet of mitral valve (shown in top photo)
      • obstructs the outflow to the aortic valve
        • leaflet is drawn open by fast moving blood being ejected during systole
      • conduction irregularities results in arrhythmias
        • cause of death
    • can be inherited
      • autosomal dominant missense mutations (most cases)
      • mutated gene in cardiac cell sarcomere proteins (commonly heavy chain of β-myosin, or troponin) 
      • associated with Friedreich's ataxia
  • Symptoms/Physical exam
    • harsh systolic ejection crescendo-decrescendo murmur heard best in apex and left sternal border. No radiation to the carotids. 
      • ↑ in intensity with decreased preload
        • results from ↑ contraction (therefore ↑ thickening) of the septal wall, which causes ↑ in outflow obstruction
        • can be observed by having the patient go from a squatting to a standing position
  • Evaluation
    • echocardiography is diagnostic and shows
      • asymetrically thickened LV walls
      • involving the interventricular septum
      • but may show normal EF
      • can show concentric ventricular hypertrophy
    • histological examination shows tangled, disoriented myofibrils 
  • Treatment includes
    • beta-blockers
    • calcium channel blockers
      • non-dihydropyridine type (e.g. verapamil)
    • disopyramide
    • septoplasty - in severe cases
    • certain medications and therapies should be avoided including
      • inotropes (i.e. digoxin)
      • vasodilators
      • overdiuresis because decreased blood volume in ventricle increases probability of septum blocking the outflow tract
Restrictive Cardiomyopathy
  • Overview
    • least common of the cardiomyopathies
    • most caused by chronic, progressive, infiltrative or metabolic diseases including
      • amyloidosis
        • transthyretin
          • senile cardiac amyloidosis
            • can accumulate over a lifetime and lead to asymptomatic diastolic dysfunction in the elderly
          • familial amyloid cardiomyopathy
            • mutated transthyretin can deposit in the heart and lead to a symptomatic restrictive cardiomyopathy
      • sarcoidosis
      • hemochromatosis  
      • cancer
      • endocardial fibroelastosis
        • non-compliant endocardium of children
      • Loffler's endocardial fibrosis
        • eosinophilic infiltrate with endomyocardial fibrosis with or without presence of parasitic infection
      • glycogen storage diseases
        • Pompe's disease
    • regardless of cause the functional deficit is a ↓ in ventricular compliance
  • Symptoms/Physical exam
    • patients often present with chronic, progressively worsening diastolic dysfunction
  • Evaluation
    • echocardiography is diagnostic
      • shows LVH
    • tissue biopsy is required
      • to determine underlying cause
    • EKG demonstrates arrhythmias
      • low voltage


  RATE CONTENT
4.0
AVERAGE 4.0 of 7 RATINGS

Qbank (6 Questions)

TAG
(M1.CV.1) A 19-year-old basketball player unexpectedly collapses on the court. Several minutes later he returns to consciousness and is able to continue playing. This has happened several times before with similar outcomes. He had no significant past medical history. Which of the following is most likely to be found in this patient? Topic Review Topic

1. Atheromatous plaque rupture
2. Coagulation necrosis with loss of nuclei and striations
3. Septal hypertrophy
4. Postductal coarctation of the aorta
5. Cardiac myxoma

PREFERRED RESPONSE ▶
TAG
(M1.CV.12) A 12-year-old female with an autosomal dominant mutation in myosin-binding protein C is being evaluated by a pediatric cardiologist. The family history reveals that the patient's father died suddenly at age 33 while running a half-marathon. What was the likely finding on histological evaluation of his father's heart at autopsy? Topic Review Topic

1. Myocyte disarray
2. Amyloid deposits
3. Eosinophilic infiltration
4. Wavy myocytes
5. Viral particles

PREFERRED RESPONSE ▶
TAG
(M1.CV.20) A 49-year-old man presents to his physician complaining of weakness and fatigue. On exam, you note significant peripheral edema. Transthoracic echocardiogram is performed and reveals a preserved ejection fraction with impaired diastolic relaxation. A representative still image is shown in Image A. Which of the following is likely the cause of this patient's symptoms? Topic Review Topic
FIGURES: A          

1. Previous treatment with doxorubicin
2. Hemochromatosis
3. Heavy, long-term alcohol consumption
4. History of myocardial infarction
5. History of a recent viral infection

PREFERRED RESPONSE ▶
TAG
(M1.CV.103) An 18-year-old African-American male presents to his family physician for a routine sports physical. He has a family history of sudden death at a young age. Upon physical examination the physician appreciates a systolic murmur. The intensity of the murmur increases when performing a valsalva maneuver. The physician refers the patient for an EKG, which is attached. What is the most likely cause of this murmur? Topic Review Topic
FIGURES: A          

1. Aortic valve stenosis
2. Mitral stenosis
3. Tricuspid stenosis
4. Hypertrophic cardiomyopathy
5. Benign systolic flow murmur

PREFERRED RESPONSE ▶
TAG
(M1.CV.140) A 66-year-old female with a past medical history significant for hypertension and breast cancer that is in remission after chemotherapy, presents to her primary care physician complaining of progressive dyspnea, decreased exercise tolerance, and paroxysmal nocturnal dyspnea. On chest auscultation you note an S3. A chest radiograph and echocardiogram are shown in Figure A. Which of the following medications is likely responsible for the patient's current presentation? Topic Review Topic
FIGURES: A          

1. Lisinopril
2. Digoxin
3. Cytarabine
4. Hydrochlorothiazide
5. Doxorubicin

PREFERRED RESPONSE ▶
TAG
(M1.CV.219) A 19-year-old Caucasian male collapsed from sudden cardiac arrest while playing in a college basketball game. Attempts at resuscitation were unsuccessful. Post-mortem pathologic and histologic examination found asymmetric left ventricular hypertrophy and myocardial disarray. Assuming this was an inherited condition, the relevant gene most likely affects which of the following structures? Topic Review Topic

1. Cardiac cell sarcomere proteins
2. Membrane potassium channel proteins
3. Ryanodine receptors
4. Autoimmune beta-cell antibodies
5. Membrane sodium channels

PREFERRED RESPONSE ▶
This is a Never-Been-Seen Question that can only be seen in Study Plan Mock Exams.
Access to 600+ Questions not available in Free Qbank



Evidence & References Show References




Topic Comments

Subscribe status: